In a small bowl, whisk together flour, cornmeal, salt, baking powder, black pepper and cayenne pepper.

In a large bowl, stir together corn, milk, egg, sugar and the whites of the scallions until well combined. Add flour mixture and stir until combined.

Evenly divide the mixture between the wells of 12 12-cup miniature muffin tins lightly coated with cooking spray (about 1 tablespoon of the batter per well). Place into the oven and bake until the centers are just set, about 8 to 12 minutes. Remove and use a thin knife to loosen corn cakes from the pan - add small dollops of sour cream on each one and top with the leftover scallion greens to serve.